Iron nanomedicines induce Toll-like receptor activation, cytokine production and complement activation

Publication date: March 2017
Source:Biomaterials, Volume 119
Author(s): Johan J.F. Verhoef, A. Marit de Groot, Marc van Moorsel, Jeffrey Ritsema, Nataliia Beztsinna, Coen Maas, Huub Schellekens
Approximately a dozen of intravenous iron nanomedicines gained marketing authorization in the last two decades. These products are generally considered as safe, but have been associated with an increased risk for hypersensitivity-like reactions of which the underlying mechanisms are unknown. We hypothesized that iron nanomedicines can trigger the innate immune system. We hereto investigated the physico-chemical properties of ferric gluconate, iron sucrose, ferric carboxymaltose and iron isomaltoside 1000 and comparatively studied their interaction with Toll-like receptors, the complement system and peripheral blood mononuclear cells. Two out of four formulations appeared as aggregates by Scanning Transmission Electron Microscopy analysis and were actively taken up by HEK293T- and peripheral blood mononuclear cells in a cholesterol-dependent manner. These formulations triggered in vitro activation of intracellular Toll-like receptors 3, -7 and -9 in a dose- and serum-dependent manner. In parallel experiments, we determined that these compounds activated the complement system. Finally, we found that uptake of aggregation-prone iron nanomedicines by peripheral blood mononuclear cells in whole blood induced production of the proinflammatory cytokine IL-1β, but not IL-6.



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Editorial board

Publication date: February 2017
Source:Biomaterials, Volume 117





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Glucose modulates antimicrobial photodynamic inactivation of Candida albicans in biofilms

Publication date: Available online 18 December 2016
Source:Photodiagnosis and Photodynamic Therapy
Author(s): Luis Cláudio Suzuki, Ilka Tiemy Kato, Renato Araujo Prates, Caetano Padial Sabino, Tania Mateus Yoshimura, Tamires Oliveira Silva, Martha Simões Ribeiro
Candida albicans biofilm is a main cause of infections associated with medical devices such as catheters, contact lens and artificial joint prosthesis. The current treatment comprises antifungal chemotherapy that presents low success rates. Photodynamic inactivation (PDI) involves the combination of a photosensitizing compound (PS) and light to generate oxidative stress that has demonstrated effective antimicrobial activity against a broad-spectrum of pathogens, including C. albicans. This fungus senses glucose inducing an upregulation of membrane transporters that can facilitate PS uptake into the cell. The aim of this study was to evaluate the effects of glucose on methylene blue (MB) uptake and its influence on PDI efficiency when combined to a red LED with central wavelength at λ=660nm. C. albicans biofilms were grown on hydrogel disks. Prior to PDI assays, MB uptake tests were performed with and without glucose-sensitization. In this system, the optimum PS administration was determined as 500μM of MB in contact with the biofilm during 30min before irradiation. Irradiation was performed during 3, 6, 9, 12, 15 and 18min with irradiance of 127.3mW/cm². Our results showed that glucose was able to increase MB uptake in C. albicans cells. In addition, PDI without glucose showed a higher viability reduction until 6min; after 9min, glucose group demonstrated a significant decrease in cell viability when compared to glucose-free group. Taking together, our data suggest that glucose is capable to enhance MB uptake and modulate photodynamic inactivation of C. albicans biofilm.

Graphical abstract

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Multicolor imaging of hydrogen peroxide level in living and apoptotic cells by a single fluorescent probe

Publication date: 15 May 2017
Source:Biosensors and Bioelectronics, Volume 91
Author(s): Ying Wen, Fengfeng Xue, Haichuang Lan, Zhenhua Li, Shuzhang Xiao, Tao Yi
To understand the entangled relationship between reactive oxygen species (ROS) and apoptosis, there is urgent need for simultaneous dynamic monitoring of these two important biological events. In this study, we have developed a fluorescent probe, pep4-NP1, which can simultaneously detect H2O2 and caspase 3, the respective markers of ROS and apoptosis. The probe contains a H2O2 fluorescence reporter (NP1) and Cy5 fluorescent chromophore connected by a caspase 3 specific recognition peptide. The detecting strategy was realized through a controllable fluorescence resonance energy transfer (FRET) process between NP1 and Cy5 of pep4-NP1, after reaction with H2O2, which was verified by molecular calculation and in vitro spectral studies. In the absent of caspase 3, the accumulation of H2O2 induces red fluorescence of pep4-NP1 centered at 663nm in living cells due to the existence of FRET. In contrast, FRET is inhibited in apoptotic cells due to cleavage of the peptide spacer of pep4-NP1 by over-expressed caspase 3. Consequently, green fluorescence (555nm) predominated when labelling production of H2O2 in apoptotic cells. Moreover, Pep4-NP1 shows excellent selectivity towards H2O2 and caspase 3 on their respective reaction sites. Therefore, pep4-NP1 can distinguish endogenously generated H2O2 between living cells and apoptotic cells with different fluorescence wavelengths, providing additional information on the ROS production pathways.



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Unilateral chronic pain may neglect the healthy side

Publication date: Available online 18 December 2016
Source:Cortex
Author(s): Sophie Jacquin-Courtois, Laure Christophe, Eric Chabanat, Karen T. Reilly, Yves Rossetti




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The “Proust Phenomenon”: odor-evoked autobiographical memories triggered by direct amygdala stimulation in human

Publication date: Available online 18 December 2016
Source:Cortex
Author(s): Fabrice Bartolomei, Stanislas Lagarde, Samuel Médina Villalon, Aileen McGonigal, Christian G. Benar




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Functional anatomy of the macaque temporo-parieto-frontal connectivity

Publication date: Available online 18 December 2016
Source:Cortex
Author(s): Elena Borra, Giuseppe Luppino
The primate parietal lobe is primarily dedicated to the processing of sensory information for the guidance of motor behavior, based on the integration of sensory with motor signals (sensorimotor transformations), mediated by specific, strong, and reciprocal connections with the motor cortex. Sensorimotor transformations have been regarded as an automatic process carried out independently from the temporal cortex, which is considered the location where sensory information is used for perceptual processes. However, both human and non-human primate studies have shown interactions between these two regions in different aspects of sensorimotor and cognitive processes. Connectional studies in macaques have provided a detailed description of the possible neural substrate for these interactions. Specifically, temporo-parietal connections almost exclusively involve the inferior parietal lobule (IPL) and display a fine topographic organization, providing the substrate for the role of the macaque IPL in "perception-based" control of motor behavior. Particularly, more rostral IPL areas are involved in motor and cognitive motor functions related to hand action organization and oculomotor control as well as in action and intention understanding, whereas more caudal IPL areas are involved in multisensory integration for the construction of space representations for guiding arm and eye motor behavior. Temporal and IPL-interconnected areas also share connections with specific ventral frontal areas and are thus part of large-scale cortical networks in which the various nodes are linked through "dorsal" temporo-parieto-frontal and "ventral" temporo-frontal pathways. Anatomical and functional studies suggest homologies between human and macaque temporo-parieto-frontal connectivity; they also suggest that higher-order functions of the human IPL could have evolved from the exploitation and adaptation of phylogenetically older neural mechanisms that occur in macaque brains. Thus, connectional data from macaque studies appear essential for understanding human brain mechanisms, even in cases of cognitive abilities undeveloped in other animals, and for interpreting clinical data, including disconnection syndromes.



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How specialized are writing-specific brain regions? An fMRI study of writing, drawing and oral spelling

Publication date: Available online 18 December 2016
Source:Cortex
Author(s): Samuel Planton, Marieke Longcamp, Patrice Péran, Jean-François Démonet, Mélanie Jucla
Several brain imaging studies identified brain regions that are consistently involved in writing tasks; the left premotor and superior parietal cortices have been associated with the peripheral components of writing performance as opposed to other regions that support the central, orthographic components. Based on a meta-analysis by Planton, Jucla, Roux, and Demonet (2013), we focused on five such writing areas and questioned the task-specificity and hemispheric lateralization profile of the brain response in an fMRI experiment where 16 right-handed participants wrote down, spelled out orally object names, and drew shapes from object pictures. All writing-related areas were activated by drawing, and some of them by oral spelling, thus questioning their specialization for written production. The graphemic/motor frontal area, a subpart of the superior premotor cortex close to Exner's area (Roux et al., 2009), was the only area with a writing-specific lateralization profile, that is, clear left lateralization during handwriting, and bilateral activity during drawing. Furthermore, the relative lateralization and levels of activation in the superior parietal cortex, ventral premotor cortex, ventral occipitotemporal cortex and right cerebellum across the three tasks brought out new evidence regarding their respective contributions to the writing processes.



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Stimulus uncertainty enhances long-term potentiation-like plasticity in human motor cortex

Publication date: Available online 18 December 2016
Source:Cortex
Author(s): Martin V. Sale, Abbey S. Nydam, Jason B. Mattingley
Plasticity can be induced in human cortex using paired associative stimulation (PAS), which repeatedly and predictably pairs a peripheral electrical stimulus with transcranial magnetic stimulation (TMS) to the contralateral motor region. Many studies have reported small or inconsistent effects of PAS. Given that uncertain stimuli can promote learning, the predictable nature of the stimulation in conventional PAS paradigms might serve to attenuate plasticity induction. Here, we introduced stimulus uncertainty into the PAS paradigm to investigate if it can boost plasticity induction. Across two experimental sessions, participants (n = 28) received a modified PAS paradigm consisting of a random combination of 90 paired stimuli and 90 unpaired (TMS-only) stimuli. Prior to each of these stimuli, participants also received an auditory cue which either reliably predicted whether the upcoming stimulus was paired or unpaired (no uncertainty condition) or did not predict the upcoming stimulus (maximum uncertainty condition). Motor evoked potentials (MEPs) evoked from abductor pollicis brevis muscle quantified cortical excitability before and after PAS. MEP amplitude increased significantly 15 minutes following PAS in the maximum uncertainty condition. There was no reliable change in MEP amplitude in the no uncertainty condition, nor between post-PAS MEP amplitudes across the two conditions. These results suggest that stimulus uncertainty may provide a novel means to enhance plasticity induction with the PAS paradigm in human motor cortex. To provide further support to the notion that stimulus uncertainty and prediction error promote plasticity, future studies should further explore the time course of these changes, and investigate what aspects of stimulus uncertainty are critical in boosting plasticity.



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The role of the IFG and pSTS in syntactic prediction: evidence from a parametric study of hierarchical structure in fMRI

Publication date: Available online 18 December 2016
Source:Cortex
Author(s): William Matchin, Christopher Hammerly, Ellen Lau
Sentences encode hierarchical structural relations among words. Several neuroimaging experiments aiming to localize combinatory operations responsible for creating this structure during sentence comprehension have contrasted short, simple phrases and sentences to unstructured controls. Some of these experiments have revealed activation in the left inferior frontal gyrus (IFG) and posterior superior temporal sulcus (pSTS), associating these regions with basic syntactic combination. However, the wide variability of these effects across studies raises questions about this interpretation. In an fMRI experiment, we provide support for an alternative hypothesis: these regions underlie top-down syntactic predictions that facilitate sentence processing but are not necessary for building syntactic structure. We presented stimuli with three levels of structure: unstructured lists, two-word phrases, and simple, short sentences; and two levels of content: natural stimuli with real words and stimuli with open-class items replaced with pseudowords (jabberwocky). While both the phrase and sentence conditions engaged syntactic combination, our experiment only encouraged syntactic prediction in the sentence condition. We found increased activity for both natural and jabberwocky sentences in the left IFG (pars triangularis and pars orbitalis) and pSTS relative to unstructured word lists and two-word phrases, but we did not find any such effects for two-word phrases relative to unstructured word lists in these areas. Our results are most consistent with the hypothesis that increased activity in IFG and pSTS for basic contrasts of structure reflects syntactic prediction. The pars opercularis of the IFG showed a response profile consistent with verbal working memory. We found incremental effects of structure in the anterior temporal lobe (ATL), and increased activation only for sentences in the angular gyrus/temporal-parietal junction (AG/TPJ) – both regions showed these effects for stimuli with all real words. These findings support a role for the ATL in semantic combination and the AG/TPJ in thematic processing.



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Bimetal-organic frameworks/polymer core-shell nanofibers derived heteroatom-doped carbon materials as electrocatalysts for oxygen reduction reaction

Publication date: April 2017
Source:Carbon, Volume 114
Author(s): Qijian Niu, Junxia Guo, Binling Chen, Jun Nie, Xindong Guo, Guiping Ma
In this work, Zn-Co-ZIF-n(shell)/PAN(core) nanofibers were well-designed and prepared through bimetal zeolitic imidazolate frameworks (ZIFs) grown on the surface of 2-Methylimidazole/Polyacrylonitrile (MIM/PAN) electrospun nanofibers. After carbonization of Zn-Co-ZIF-n/PAN nanofibers (n was the molar ratio of Zn/Co before carbonization), the core layer was converted to nitrogen-doped carbon nanofibers (NCNFs) and the shell layer was converted to Zn/Co bimetal nanoparticles coated with graphitic carbon layer (Zn/Co@C). It was found that Zn/Co@C-NCNFs are featured with hierarchical network structure and high surface area. Further doped by nitrogen species and embedded by Zn/Co bimetal nanoparticles, it exhibited excellent electrocatalytic performance for oxygen reduction reaction (ORR), better than the reference samples. By further investigating the electrocatalytic performance, the optimized sample Zn/Co@C-NCNFs (0.50) derived from Zn-Co-ZIF-0.50/PAN at 800 °C carbonization exhibited excellent electrocatalytic activity (the onset and half-wave potentials were −0.099 V and −0.20 V vs. Ag/AgCl, respectively and nearly four electron selectivity (3.69)). Moreover, its methanol tolerance and duration stability was better than that of the commercial 20 wt% Pt/C. It provides an effective strategy to design non-precious metal electrocatalysts from the Zn-Co-ZIF-n/PAN nanofibers or other MOFs/polymer nanofibers for ORR in fuel cells.

Graphical abstract

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Metal homeostasis in infectious disease: recent advances in bacterial metallophores and the human metal-withholding response

Publication date: April 2017
Source:Current Opinion in Chemical Biology, Volume 37
Author(s): Wilma Neumann, Anmol Gulati, Elizabeth M Nolan
A tug-of-war between the mammalian host and bacterial pathogen for nutrients, including first-row transition metals (e.g. Mn, Fe, Zn), occurs during infection. Here we present recent advances about three metal-chelating metabolites that bacterial pathogens deploy when invading the host: staphylopine, staphyloferrin B, and enterobactin. These highlights provide new insights into the mechanisms of bacterial metal acquisition and regulation, as well as the contributions of host-defense proteins during the human innate immune response. The studies also underscore that the chemical composition of the microenvironment at an infection site can influence bacterial pathogenesis and the innate immune system.



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Distal Pb-Zn-Ag veins associated with the world-class Donggou porphyry Mo deposit, southern North China craton

Publication date: April 2017
Source:Ore Geology Reviews, Volume 82
Author(s): Zhan-Ke Li, Shi-Jian Bi, Jian-Wei Li, Wen Zhang, David R. Cooke, David Selby
The southern North China craton hosts numerous world-class porphyry Mo and Pb-Zn-Ag vein deposits. Whether or not the Pb-Zn-Ag veins are genetically associated with the porphyry Mo system remains contentious. Here we focus on the genetic relationships between the Sanyuangou Pb-Zn-Ag vein deposit and the world-class Donggou porphyry Mo deposit, and discuss the potential implications from the spatial and temporal relationships between porphyry and vein systems in the southern North China craton.At Sanyuangou, vein-hosted sulfide mineralization mainly comprises pyrite, sphalerite, and galena, with minor chalcopyrite, pyrrhotite, bornite, tetrahedrite, covellite, polybasite and argentite. The mineralization is hosted by a quartz diorite stock, which has a zircon U-Pb age of 1756±9Ma. However, sericite from alteration selvages of Pb-Zn-Ag sulfide mineralization yields a well-defined ⁴⁰Ar/³⁹Ar plateau age of 115.9±0.9Ma. Although nominally younger, the sericite ⁴⁰Ar/³⁹Ar age is similar to the age of the nearby Donggou porphyry Mo deposit (zircon U-Pb age of 117.8±0.9; molybdenite Re-Os ages of 117.5±0.8Ma and 116.4±0.6Ma). Pyrite from Donggou has elevated contents of Mo and Bi, whereas pyrite from Sanyuangou is enriched in Cu, Zn, Pb, Ag, Au, and As. This trace element pattern is consistent with metal zonation typically observed in porphyry related metallogenic systems. Pyrite grains from Sanyuangou have lead isotopes overlapping those from Donggou (17.273–17.495 vs. 17.328–17.517 for ²⁰⁶Pb/²⁰⁴Pb, 15.431–15.566 vs. 15.408–15.551 for ²⁰⁷Pb/²⁰⁴Pb, and 37.991–38.337 vs. 38.080–38.436 for ²⁰⁸Pb/²⁰⁴Pb). Collectively, the geological, geochronological, and geochemical data support a magmatic-hydrothermal origin for the Sanyuangou Pb-Zn-Ag deposit and confirm that the Pb-Zn-Ag veins and the Donggou Mo deposit form a porphyry-related magmatic-hydrothermal system.Given the widespread Pb-Zn-Ag veins and Mo mineralized porphyries in many districts of the southern North China craton, the model derived from this study has broad implications for further exploration of Mo and Pb-Zn-Ag resources in the area.

Graphical abstract

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Genesis of Luobuzhen Pb–Zn veins: Implications for porphyry Cu systems and exploration targeting at Luobuzhen-Dongshibu in western Gangdese belt, southern Tibet

Publication date: April 2017
Source:Ore Geology Reviews, Volume 82
Author(s): Xiang Sun, Youye Zheng, Miao Li, Haitao Ouyang, Qiangqiang Liu, Xinkui Jing, Guoping Sun, Qingjie Song
Porphyry systems are known to form in magmatic arc environment and commonly include porphyry Cu, epithermal Pb–Zn–Au–Ag, skarn polymetallic mineralization, etc. The systems are rarely reported in collisional zones, such as the Gangdese belt in southern Tibet where many postcollisional porphyry copper deposits occurred. In addition, other types of mineral systems are rarely present except porphyry copper mineralization in the Gangdese belt. In this study, we present Pb–Zn-bearing quartz veins at Luobuzhen in the western Gangdese belt. The Luobuzhen Pb–Zn veins cross-cut dacite of the Linzizong Group with zircon U–Pb age of 50.1±0.2Ma and monzogranite with zircon U–Pb age of 17.1±0.1Ma. Ore minerals include sphalerite, galena, chalcopyrite, and pyrite; gangue minerals are quartz with minor chlorite and sericite. Primary fluid inclusions of quartz are liquid-rich, aqueous, and two-phase inclusions. The homogenization temperatures of these primary inclusions are moderate to high (267–400°C), and salinities range from 8.9 to 18.4wt.% NaCl equiv. Quartz has δ¹⁸OSMOW values of 6.2–9.3‰, while sulfides have δ³⁴SV-CDT values of −5.1‰ to 0.1‰, ²⁰⁶Pb/²⁰⁴Pb of 18.722–18.849, ²⁰⁷Pb/²⁰⁴Pb of 15.640–15.785, and ²⁰⁸Pb/²⁰⁴Pb of 39.068–39.560. These data suggest that magmatic fluids with contribution from meteoric water, magmatic sulfur, and lead derived from upper crust and metasomatized mantle by Indian continental materials would be critical for the Luobuzhen base metal mineralization.The Dongshibu area, located at ∼2km east of the Luobuzhen, is characterized by high concentrations of Cu (up to 1450ppm) and Mo (up to 130ppm) of stream sediments, which is quite different from high concentrations in Pb, Zn, Ag, and Au shown in the Luobuzhen area. In addition, porphyry copper mineralization-related alteration and veins/veinlets occur in the Miocene monzogranite at Dongshibu. The monzogranite is characterized by high Sr/Y ratios, which are also shown on ore-forming intrusions in the Gangdese postcollisional porphyry copper deposits, and shows similar zircon Hf isotopes to the ore-related high Sr/Y intrusions from the Zhunuo porphyry copper deposit which is located ∼20km northeast of the Luobuzhen-Dongshibu. A comprehensive analysis allows us to infer that the base metal veins at Luobuzhen are components of a porphyry Cu system with porphyry Cu mineralization likely present at Dongshibu and epithermal Au–Ag veins possibly occurring at Luobuzhen, which are indicative of the existence of porphyry copper systems in collisional zones. The potential porphyry Cu mineralization and epithermal Au–Ag veins should be targeted in future exploration at Luobuzhen-Dongshibu.

Graphical abstract

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NIPTL-Novo: Non-isobaric peptide termini labeling assisted peptide de novo sequencing

Publication date: 10 February 2017
Source:Journal of Proteomics, Volume 154
Author(s): Shen Zhang, Yichu Shan, Shurong Zhang, Zhigang Sui, Lihua Zhang, Zhen Liang, Yukui Zhang
A simple and effective de novo sequencing strategy assisted by non-isobaric peptide termini labeling, NIPTL-Novo, was established. The y-series ions and b-series ions of peptides can be clearly distinguished according to the different mass tags incorporated in N-terminus and C-terminus. This is helpful for improving the accuracy of peptide sequencing and increasing the sequencing speed. For the spectra commonly identified by both de novo sequencing and database searching software (Mascot or Maxquant), NIPTL-Novo gave identical result to more than 85% of these spectra. Furthermore, the quantitative profiling of the sample can be performed simultaneously along with de novo sequencing. Finally, this strategy can be applied to discover the peptides with potential mutation sites by combining with mass-defect based isotopic labeling.SignificanceThe aim of the research presented in this paper is to establish a simple but effective de novo sequencing strategy based on non-isobaric peptide termini labeling, named NIPTL-Novo. First, different mass tags incorporated in N-terminus and C-terminus generated by non-isobaric peptide termini labeling will help to distinguish both b and y ion series, which significantly simplify the MS/MS spectra and reduce the time consumption for de novo sequencing. Second, the isolation window of this strategy is just 4Da, much smaller than most existed labeling assisted de novo sequencing methods, which reduces the interferences caused by co-fragmentation ions. Third, the quantitative profiling of the sample can be performed simultaneously along with the de novo sequencing, and the quantitative accuracy is comparable to other chemical labeling methods. Finally, this strategy was expanded to the analysis of peptide mutation with combination of mass-defect based labeling, and two reliable mutated peptides were discovered.

Graphical abstract

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Development of highly reinforced acrylonitrile butadiene rubber composites via controlled loading of sol-gel titania

Publication date: 27 January 2017
Source:Polymer, Volume 109
Author(s): Chayan Das, Naresh D. Bansod, Bharat P. Kapgate, Uta Reuter, Gert Heinrich, Amit Das
Remarkable improvement in mechanical properties of acrylonitrile butadiene rubber (NBR) composites is achieved by incorporating nano-titania that is synthesised in solution of the raw rubber using titanium n-butoxide (TNB) as the titania precursor. This is achieved by designed and controlled incorporation of titania that resulted in very good dispersion of titania of nanometric dimension in rubber matrix and enhanced rubber-filler interaction. This sol-gel transformation is carried out under optimised reaction condition. Surface modification of titania by a silane coupling agent (bis-(3-triethoxysilylpropyl)-tetrasulfide, TESPT) causes further improvement in filler dispersion and composite properties when added in the reactive sol-gel system during in situ titania generation rather than it's external addition in the titania filled NBR during mixing and compounding. Thorough characterisation of the composites are done that encompasses a wide range of studies on thermal, morphological, mechanical, dielectric, dynamic mechanical, rheological and antifungal properties. The results are analysed on a comparative basis to investigate the effect of in situ incorporation and in situ surface modification of titania on the composite properties.

Graphical abstract

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Interlayer-expanded MoS2

Publication date: Available online 16 December 2016
Source:Materials Today
Author(s): Kowsalya Devi Rasamani, Farbod Alimohammadi, Yugang Sun
Motivated by the novel properties of two-dimensional materials, MoS2 has been extensively explored with discoveries surging in the recent years. Such impressive progress benefits from the success in synthesizing nanostructured MoS2 with precisely controlled parameters including edge density and crystalline phase. In this review, we focus on the synthesis of MoS2 with expanded interlayer spacing and their applications in energy storage, catalysis and environmental remediation, highlighting the importance of tuning interlayer spacing on improving performance of MoS2. The challenges faced in this emerging research area and perspective research directions are also discussed.



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IDD Newsletter November 2016

IDD NEWSLETTER – November 2015 (PDF File, 9.42 MB)
VOLUME 44 NUMBER 4 NOVEMBER 2016
IODINE GLOBAL NETWORK (formerly ICCIDD Global Network) is a nongovernmental organization dedicated to sustained optimal iodine
nutrition and the elimination of iodine deficiency throughout the world.

The post IDD Newsletter November 2016 appeared first on American Thyroid Association.

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MRI-guided breast vacuum biopsy: Localization of the lesion without contrast-agent application using diffusion-weighted imaging

Publication date: May 2017
Source:Magnetic Resonance Imaging, Volume 38
Author(s): Nicole Berger, Zsuzsanna Varga, Thomas Frauenfelder, Andreas Boss
ObjectiveIn magnetic resonance-guided breast vacuum biopsies, the contrast agent for targeting suspicious lesions can typically be applied only once during an intervention, due to the slow elimination of the gadolinium chelate from the extracellular fluid space. This study evaluated the feasibility of diffusion-weighted imaging (DWI) for lesion targeting in vacuum assisted magnetic resonance imaging (MRI) biopsies.ConclusionDWI may be used as an alternative to dynamic contrast-enhanced MRI with the advantage of reproducibility. However, the targeted lesion requires the characteristics of a mass-like lesion, substantial diffusion restriction, and a minimum size of approximately 1cm.



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The impact of spin coupling signal loss on fat content characterization in multi-echo acquisitions with different echo spacing

Publication date: May 2017
Source:Magnetic Resonance Imaging, Volume 38
Author(s): K. Nikiforaki, G.C. Manikis, T. Boursianis, K. Marias, A. Karantanas, T.G. Maris
PurposeThis study aimed to assess the effect of echo spacing in transverse magnetization (T2) signal decay of gel and fat (oil) samples. Additionally, we assess the feasibility of using spin coupling as a determinant of fat content.MethodsPhantoms of known T2 values, as well as vegetable oil phantoms, were scanned at 1.5T scanner with a multi echo FSE sequence of variable echo spacing above and below the empirical threshold of 20ms for echo train signal modulation (6.7, 13.6, 26.8, and 40ms). T2 values were calculated from monoexponential fitting of the data. Relative signal loss between the four acquisitions of different echo spacing was calculated.ResultsAgreement in the T2 values of water gel phantom was observed in all acquisitions as opposed to fat phantom (oil) samples. Relative differences in signal intensity between two successive sequences of different echo spacing on composite fat/water regions of interest was found to be linearly correlated to fat fraction of the ROI.ConclusionThe sample specific degree of signal loss that was observed between different fat samples (vegetable oils) can be attributed to the composition of each sample in J coupled fat components. Hence, spin coupling may be used as a determinant of fat content.



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